JP2003081489A - Paper carrying device and image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the accuracy of aligning paper perpendicularly to a carrying direction. SOLUTION: This paper carrying device comprises a drive roller 39 for carrying the paper nipped in a space to a pinch roller 40, moving means having a power transmission mechanism containing a rack member 50 movably provided on a roller shaft 41 of the drive roller 39 and a pinion gear 53 engaging therewith, for moving the drive roller 39 perpendicularly to the carrying direction of the paper via the power transmission mechanism integrally with the roller shaft 41, a coil spring 59 for energizing the roller shaft 41 via the rack member 50 perpendicularly to the carrying direction, and a coil spring 63 for energizing the roller shaft 41 oppositely to the direction of energization by the coil spring 59.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus such as a copying machine or a printer, and more particularly to a sheet conveying apparatus suitable for use in the image forming apparatus.

[0002]

2. Description of the Related Art In general, an image forming apparatus such as a copying machine or a printer uses a sheet conveying apparatus for conveying a sheet to be image-formed. In addition, a paper conveying device used in the image forming apparatus is orthogonal to the conveying direction in order to align the position of the image with the position of the paper at the image output position where the image is output (transferred) to the paper. Some have a mechanism for moving a sheet in a direction (hereinafter referred to as a side shift mechanism).

In this type of sheet conveying apparatus, before the sheet is sent to the image output position, the sheet is nipped (sandwiched) by the sheet conveying roller and the sheet conveying roller is moved in a direction orthogonal to the sheet conveying direction. The image and paper are aligned (aligned). As a side shift mechanism for realizing this, one using a gear train is known.

[0004]

However, in the sheet conveying device using the gear train in the side shift mechanism,
There was a problem that the position of the paper was misaligned due to the backlash in the meshing part of the gears.

As a countermeasure against this, for example, Japanese Patent Laid-Open No. 11-18
Japanese Patent No. 9355 discloses a configuration in which a rack member is mounted on a roller shaft of a conveying roller, a coil spring is locked to the rack member, and a pulling force of the coil spring acts on the rack member. It is difficult to reliably prevent displacement of the transport roller due to backlash, and the transport roller stop position (paper alignment position) due to rattling of the rack member on the roller shaft and inertial force that acts when the transport is stopped. However, there is a problem that variations easily occur. Further, since a tension type coil spring is used, there is a drawback that a space for mounting the spring must be separately secured in the peripheral portion of the roller shaft.

[0006]

A sheet conveying device according to the present invention is provided with a conveying roller for nipping and conveying a sheet, and a roller shaft of the conveying roller so as to be movable in the axial direction of the roller shaft. A power transmission mechanism including a first gear member and a second gear member that meshes with the first gear member;
Moving means for moving the conveying roller integrally with the roller shaft in the direction orthogonal to the sheet conveying direction via the power transmission mechanism, and biasing the roller shaft in the direction orthogonal to the conveying direction via the first gear member. The first urging means and the roller shaft to the first
And a second urging means for urging the urging means in a direction opposite to the urging direction. Further, the image forming apparatus according to the present invention is equipped with the sheet conveying device having the above configuration.

In the sheet conveying device having the above structure and the image forming apparatus having the same, the rattling of the first gear member on the roller shaft is eliminated by the urging force of the first urging means. Further, when the transport roller is moved in the direction orthogonal to the transport direction, displacement of the transport roller due to inertial force or backlash acting when the movement is stopped is eliminated by the biasing force of the first and second biasing means. It

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a schematic diagram showing a configuration example of an image forming apparatus to which the present invention is applied. The illustrated image forming apparatus 1
Is mainly composed of the image reading unit 2, the image forming unit 3, and the sheet conveying device 4.

The image reading section 2 reads an image of an original set on a transparent original table (platen glass). The image reading unit 2 includes, for example, an optical scanning system including a lamp, a mirror and a carriage, a lens system for forming an optical image read and scanned by the optical scanning system, and an optical image formed by the lens system. An image reading sensor (for example, 3 line C
And a CD sensor).

The image forming section 3 includes four photosensitive drums 5, 6, 7, and 8 corresponding to K (black), Y (yellow), M (magenta), and C (cyan) colors, and the respective photosensitive drums. Four primary transfer rollers 9, 10, 1 corresponding to the body drum
1, 12, an intermediate transfer belt 13, and a secondary transfer roller 1
4, a vacuum transport unit 15, and a fixing device 16 are provided in a four-tandem tandem system.

Around the photosensitive drums 5, 6, 7, and 8, a charger and a laser writing device (laser R
OS), a developing device, a cleaner, etc. are arranged. The charging device uniformly charges the surface of the photosensitive drum, and the laser writing device forms an electrostatic latent image on the surface of the photosensitive drum charged by the charging device by laser irradiation. Further, the developing device supplies toner as a developer to the surface of the photoconductor drum to visualize (develop) the electrostatic latent image to form a toner image, and the cleaner does not need to remain on the photoconductor drum. It removes toner.

On the other hand, each primary transfer roller 9,
10, 11, and 12 are arranged in the vicinity of the corresponding photoconductor drums 5, 6, 7, and 8 so as to face each other with the intermediate transfer belt 13 interposed therebetween. These primary transfer rollers 9,
10, 11, 12 are the photosensitive drums 5, as described above.
The toner images formed on 6, 7, and 8 are transferred (primary transfer) to the intermediate transfer belt 13. The intermediate transfer belt 13 is stretched in a loop by a plurality of (five in the illustrated example) belt supporting rollers.

The secondary transfer roller 14 is the intermediate transfer belt 1.
It is arranged so as to face one of the belt supporting rollers for supporting the belt 3. The secondary transfer roller 14 and the belt supporting roller constitute an image transfer section. In this image transfer portion, the intermediate transfer belt 13 and the sheet are nipped between the secondary transfer roller 14 and the belt supporting roller facing the secondary transfer roller 14, and in this state, the polarity opposite to that of the toner applied to the secondary transfer roller 14 is applied. The toner image is transferred (secondarily transferred) from the intermediate transfer belt 13 to the sheet by the electric charge (or voltage) of. Transfer position of this toner image (secondary transfer position)
Is the image output position in the image forming unit 3. The vacuum transport unit 15 transports the sheet on which the toner image is transferred by the secondary transfer roller 14 to the fixing device 16. The fixing device 16 fixes the toner image on the sheet by heating and pressing.

On the other hand, the paper transporting device 4 includes the first tray 1
Among the papers stored in the second tray 18, the third tray 19 and the third tray 19, the paper of the tray selected by the user operation or the paper of the tray selected by the automatic selection function is set in a predetermined path. The paper is fed in. In the vicinity of each tray 17, 18, 19
The corresponding delivery rollers 20, 21, 22 are provided. Each of the delivery rollers 20, 21, 2
The numeral 2 is for separating the called sheets by separating them one by one from the corresponding trays 17, 18, 19, and sending the sheets to the downstream side in the transport direction. An operation panel 23 operated by a user is provided near the image reading unit 2.

Here, each of the delivery rollers 20, 2
In the series of paper transport paths R1 to R5 from the paper feed position of the sheets 1 and 22 to the discharge tray 24 via the image output position in the image forming section 3, rollers for paper transport are appropriately arranged. Has been done. The paper stored in the first tray 17 is sent out by the sending-out roller 20, and then sent to the merging / conveying unit 25 via the first paper conveying path R1. Further, the sheets accommodated in the second tray 18 are sent out by the sending-out roller 21, and then the merging / conveying unit 2 passes through the first sheet conveying path R1.
It is sent to 5. On the other hand, the sheets accommodated in the third tray 19 are fed by the delivery roller 22 to the merging / conveying unit 2
Directly sent to 5.

Further, the sheet sent to the merging / conveying section 25 is sent to the image output position of the image forming section 3 via the second sheet conveying path R2. Further, the sheet that has passed the image output position is sent to the fixing device 16 by the vacuum conveyance section 15, and then is ejected to the ejection tray 24 via the third sheet conveyance path R3. On the other hand, the paper on which images are formed on both sides (first side and second side) is the fixing device 16
After passing through the sheet, the sheet is sent to the double-sided reversing unit 28 via the fourth sheet transporting path R4, the direction of the sheet is changed for reversing the sheet, and then the sheet is merged again via the fifth sheet transporting path R5. It is sent to the transport unit 25.

In such paper transport paths R1 to R5, a paper aligning section 26 and a registration roller 27 are arranged in the second paper transport path R2. The sheet aligning unit 26
This is a portion for performing skew correction of the sheet conveyed along the second sheet conveying path R2. The configuration of the sheet aligning unit 26 will be described later. The registration roller 27 is composed of a pair of rollers held in pressure contact with each other, and nips the paper between the pair of rollers while feeding the paper to the image output position by the rotation of the rollers.

When the registration roller 27 feeds the paper, the timing adjustment means (not shown) adjusts the arrival timing of the paper with respect to the image output position. The timing adjusting means varies the conveyance speed of the paper by the registration roller 27 based on the timing when a paper passage sensor (described later) provided in front of (on the upstream side of) the registration roller 27 detects the passage of the paper. According to the arrival timing of the toner image at the image output position, the arrival timing of the paper at the image output position is adjusted.

Further, curl correction units 29 and 30 are provided on the paper transport paths R3 and R5, respectively. The curl correction units 29 and 30 are for correcting the curl of the paper when the toner image is fixed by the fixing device 16.

Next, the image forming apparatus 1 having the above structure
The operation of will be described. First, when the image of the original is read by the image reading unit 2, the toner image is formed by the image forming unit 3 based on the image signal obtained by the reading. In this image forming unit 3, the four photosensitive drums 5,
While rotating 6, 7, and 8, K, Y, and K on the surface of each photosensitive drum 5, 6, 7, and 8 by a charging device, a laser writing device (laser ROS), and a developing device corresponding to each.
Toner images of M and C are sequentially formed. The toner images of the respective colors formed in this way are transferred to the primary transfer rollers 9, 10, 1.
The images 1 and 12 are sequentially transferred onto the intermediate transfer belt 13 in an overlapping manner. As a result, a multicolor (full color) toner image in which four color toners are superposed is formed on the intermediate transfer belt 13. The toner image thus formed on the intermediate transfer belt 13 is carried by the intermediate transfer belt 13 and sent to the image output position (the secondary transfer position by the secondary transfer roller 14).

On the other hand, the paper of the tray selected by the user using the operation panel 23 or the paper of the tray selected by the automatic selection function is registered by the registration roller 2 at the timing when the toner image reaches the image output position.
Sent by 7. For example, if the tray selected as described above is the first tray 17, the sheet sent by the sending roller 20 is sent to the merging / conveying unit 25 via the first sheet conveying path R1, and The sheet is sent to the image output position by the registration roller 27 via the second sheet conveyance path R2.

As a result, at the image output position of the image forming section 3, the toner image (full color image) carried on the intermediate transfer belt 13 is collectively transferred (secondarily transferred) onto the sheet by the secondary transfer roller 14. After that, the sheet is sent to the fixing device 16 by the vacuum transport unit 15, where the toner image is fixed there, and then discharged to the discharge tray 24 via the third sheet transport path R3.

Further, the paper on which images are formed on both sides (paper to be copied on both sides) is sent to the double-sided reversing unit 28 via the fourth paper conveyance path R4, and the direction is changed there for the front and back reversal. Then, the sheet is sent to the fifth sheet conveyance path R5. After that, the sheet is conveyed along the fifth sheet conveying path R5, and then the timing is adjusted by the rotation of the feed roller 31, and the sheet is fed again to the merging / conveying unit 25. After that, after the toner image is transferred and fixed on the paper in the same manner as described above, the third image is formed.
The paper is discharged to the discharge tray 24 via the paper transport path R3.

FIG. 2 is a schematic view showing the arrangement of the sheet aligning section 26 according to the embodiment of the present invention. In FIG. 2, a plurality of (three in the illustrated example) skew rollers 32, 33, 34 are sequentially provided from the upstream side to the downstream side in the sheet transport direction Y. These skew rollers 32, 33, 34 are arranged so as to be inclined at a predetermined angle with respect to the sheet transport direction Y. Also, each of the skew rollers 32, 33,
Reference numeral 34 is composed of a drive roller and a pinch roller which are held in pressure contact with each other. Of these, the drive roller is arranged as tilted as shown, but the pinch roller is arranged without tilt. Further, the drive roller and the pinch roller are arranged so as to sandwich the paper conveyance path from above and below.

As described above, each of the skew rollers 32, 33, and 34, which is composed of the pair of upper and lower rollers, nips the sheet 35 with a biasing force applied to the pinch roller by a spring or the like, and in this nip state. By rotating, the conveying force in the oblique direction is applied to the sheet 35 on the sheet conveying path. On the other hand, a long side guide 36 is arranged along the transport direction Y on one side (right side in the drawing) of the paper transport path along which the paper 35 is transported. The side guide 36 has a substantially U-shaped cross section, and integrally has a reference surface 37 along the longitudinal direction of the guide.

Further, on the downstream side of the side guide 36, the sheet side end is located several millimeters inside the sheet conveying path from a reference line (indicated by a broken line in the figure) set along the reference surface 37. A detection sensor 38 is provided. The sheet side edge detection sensor 38 is arranged between the most downstream skew roller 34 and the registration roller 27 in the sheet transport direction Y. The registration roller 27 is supported by a roller moving mechanism described later so as to be movable in a direction (arrow direction in the drawing) orthogonal to the transport direction Y.

In the sheet aligning unit 26 having the above structure, the sheet 35 fed from the upstream side in the transport direction Y is nipped in order by the skew rollers 32, 33 and 34. At that time, paper 3
5 is moved to the side guide 36 side by the rotation of each of the skew rollers 32, 33, and 34 and the accompanying conveying force in the oblique direction. As a result, the side edge of the sheet 35 is abutted against the reference surface 37 of the side guide 36. as a result,
The side edge of the sheet 35 is aligned along the reference surface 37 of the side guide 36, and thereby the skew of the sheet is corrected. Further, the sheet 35 skew-corrected by the sheet aligning unit 26 is transported to the downstream side in the transport direction Y along the reference surface 37 of the side guide 36, and the registration rollers 27.
Then, it is sequentially sent to the secondary transfer roller 14.

When the leading edge of the sheet 35 fed from the sheet aligning section 26 reaches the registration roller 27, the nip releasing means (not shown) causes the skew rollers 32, 33 ,.
The nip state of 34 is released. Next, before the sheet 35 is fed to the transfer roller 14 (image output position) by the rotation of the registration roller 27, the registration roller 27
At the same time, a so-called side shift operation is performed in which the paper 35 is moved in the direction orthogonal to the transport direction Y (leftward in FIG. 2). During the side shift operation, when the side edge of the paper 35 is detected by the paper side edge detection sensor 38, the side shift operation (paper 3
5 movement) stops. As a result, the position of the paper 35 is aligned with the position of the toner image transferred onto the paper 35 in the direction orthogonal to the transport direction Y. After that, when the trailing edge of the sheet 35 passes through the registration roller 27, the registration roller 27 moves in the opposite direction (rightward in FIG. 2) to the home position (movement start position during side shift operation).
Return to.

FIG. 3 is a schematic perspective view showing a mechanical structure including a roller moving mechanism (side shift mechanism). In FIG. 3, the registration roller 27 includes a drive roller (driving roller) 39 and a pinch roller (following roller) 40. Among these, the drive roller 39 nips the paper between the drive roller 39 and the pinch roller 40 that is in pressure contact with the drive roller 39, and conveys the paper by rotating in this nip state, and corresponds to the “conveying roller” in the present invention.

The roller shaft 41 of the drive roller 39 is rotatably and axially movably supported by a bearing member (not shown). Similarly, the roller shaft 42 of the pinch roller 40 is also supported by a bearing member (not shown) so as to be rotatable and movable in the axial direction. Each roller shaft 41, 42 has a corresponding roller 39, 40.
And is arranged in parallel with each other along the direction orthogonal to the sheet conveying direction. Roller shaft 41
The first engaging member 43 is attached to one end of the roller shaft 42 in a state in which the movement in the axial direction is restricted, and one end of the roller shaft 42 also
The second engagement member 44 is attached in a state in which the movement in the axial direction is restricted. By the way, each roller shaft 41, 42
The axial direction of is the direction orthogonal to the sheet conveying direction by the registration rollers 27.

The first engaging member 43 has a disc shape as a whole, and has a peripheral groove having a concave cross section on its outer peripheral portion.
On the other hand, the second engagement member 44 has a disk shape having a smaller diameter and a smaller plate thickness than the first engagement member 43, and the outer peripheral portion thereof is the circumference of the first engagement member 43. It is arranged so as to be engaged with the groove. As a result, each roller shaft 41, 4
2 and the rollers 39 and 40 corresponding thereto can move integrally in the axial direction.

On the other end side of the roller shaft 41, the gear 4
A gear train consisting of 5, 46 and 47 is provided. Of these, the gear 46 includes a large-diameter gear portion 46A and a small-diameter gear portion 46.
It has a two-stage structure having B integrally. This gear 4
For 6, the gear 47 meshes with the large-diameter gear portion 46A, and the gear 45 meshes with the small-diameter gear portion 46B. A motor gear 48 meshes with the gear 47.
The motor gear 48 is attached to an output shaft (rotating shaft) of a drive motor (hereinafter, referred to as a transport motor) 49 for transporting a sheet.

Further, on the other end side of the roller shaft 41, a rack member 50 is mounted outside the gear 45 (at the end of the roller shaft 41). This rack member 50
Corresponds to the "first gear member" in the present invention, and is provided on the roller shaft 41 so as to be movable in the axial direction. The rack member 50 is attached to the roller shaft 41 in a rotation-free state so as not to hinder the rotation of the roller shaft 41. Further, the rack member 50 is provided with a long hole 51 extending in the axial direction of the roller shaft 41. A slide pin 52 is engaged with the elongated hole 51, which prevents the rack member 50 from being rotated by the rotation of the roller shaft 41.

A pinion gear 53 meshes with the rack member 50. As shown in FIG. 4, the pinion gear 53 has a two-stage structure that integrally includes a large diameter gear portion 53A and a small diameter gear portion 53B. Of these, the large diameter gear portion 53A
Is arranged outside the rack member 50 and has a small-diameter gear portion 53B.
Are arranged inside the rack member 50. The large-diameter gear portion 53A meshes with the motor gear 54, and the small-diameter gear portion 53B meshes with the gear portion 50A of the rack member 50. The gear portion 50A of the rack member 50 is formed along the axial direction of the roller shaft 41. The motor gear 54 is attached to an output shaft (rotating shaft) of a side-shift drive motor (hereinafter referred to as a side-shift motor) 55.

Further, in FIG. 4, the roller shaft 41 is supported by the frame member 56 of the apparatus main body via the bearing member 57, and the roller shaft 42 is also the frame member 56 of the apparatus main body.
Is supported via a bearing member (not shown). The frame member 56 supports the respective roller shafts 41 and 42 on both sides of the drive roller 39 and the pinch roller 40 which constitute the registration roller 27.

A bracket 58 is attached to the outer surface of the frame member 56 by using fixing means such as screws. A through hole (not shown) is formed on the tip end side of the bracket 58 (on the side opposite to the fixing portion with respect to the frame member 56),
The roller shaft 41 is fitted in the through hole in a non-contact state. In addition, here, the bracket 5 is attached to the frame member 56.
Although the configuration in which 8 is attached is illustrated, a portion corresponding to the bracket 58 may be integrally formed with the frame member 56.

The above-mentioned gear 45 is butted against the bracket 58. A key and a key groove (not shown) are provided in the fitting portion of the gear 45 and the roller shaft 41, and the gear 45 and the roller shaft 41 can be integrally rotated by this. However, in the axial direction of the roller shaft 41, the gear 45 is configured to be guided and moved by a key groove (not shown).

A compression type coil spring 59 is interposed between the gear 45 and the rack member 50. The coil spring 59 corresponds to the “first urging member” in the present invention, and is mounted on the roller shaft 41 by being inserted into the roller shaft 41. Furthermore, the coil spring 5
A washer 60 is interposed between the gear 9 and the gear 45, and a washer 61 is also interposed between the coil spring 59 and the rack member 50. On the other hand, a retaining ring (E ring) 62 is attached to the outermost end of the roller shaft 41. The retaining ring 62 regulates the position of the rack member 50 on the roller shaft 41.

On the other hand, a compression type coil spring 63 is provided inside the frame member 56. Coil spring 63
Corresponds to the “second urging means” in the present invention, and is formed by being fitted into the roller shaft 41.
Is mounted on. Coil spring 63 and roller shaft 4
A washer 64 is provided between the first stepped portion 41A and a washer 65 is also provided between the coil spring 63 and the bearing member 57.

Here, the two coil springs 59,
Of the 63, the coil spring 59 urges the roller shaft 41 via the rack member 50 in a direction orthogonal to the transport direction (right direction in FIG. 4), whereas the coil spring 63 changes the urging direction of the coil spring 59. The roller shaft 41 is biased in the opposite direction (leftward in FIG. 4).

More specifically, the spring force of the coil spring 59 acts outward between the gear 45 and the rack member 50. However, since the gear 45 is abutted against the bracket 58 fixed to the frame member 56, the spring force of the coil spring 59 acts on the rack member 50 with this bracket 58 as a fixed position, and this rack force causes the rack member to move. 50 is butted against the snap ring 62. Since the snap ring 62 is fixed to the outermost end of the roller shaft 41,
The spring force of the coil spring 59 is transmitted to the retaining ring 62 via the rack member 50, and the roller shaft 41 is biased to the right in FIG. 4 by this transmission force.

On the other hand, the spring force of the coil spring 63 acts outward between the bearing member 57 and the stepped portion 41A. However, since the bearing member 57 is fixed to the frame member 56, the spring force of the coil spring 63 acts on the stepped portion 41A with this bearing member 57 as a fixed position, and the roller shaft 41 of FIG. It is biased to the left. On the roller shaft 41, the biasing force of the coil springs 63 is set to be larger than the biasing force of the coil springs 59 by appropriately determining the spring constants and the number of turns of the coil springs 59 and 63, for example.

Further, the biasing force of the coil spring 63 is set to be larger than the movement resistance force of the roller shaft 41 in the direction orthogonal to the conveying direction. The movement resistance force of the roller shaft 41 is a resistance force that acts when the roller shaft 41 is moved in a direction orthogonal to the transport direction. Therefore, the factors that affect the movement resistance of the roller shaft 41 include the roller shaft 4
1 includes frictional resistance generated at a fitting portion between the bearing member 57 and the bearing member 57, frictional resistance generated at a fitting portion between the roller shaft 42 and a corresponding bearing member (not shown), and the like.

In such a mechanical structure, when the motor gear 48 is rotated by the drive of the carry motor 49, this rotational force is transmitted to the gear 45 via the gear 47 and the gear 46. As a result, the gear 47 together with the motor gear 48,
46 and 45 rotate, and further the roller shaft 41 and the drive roller 39 rotate together with the gear 45. At this time, if the pinch roller 40 is pressed against the drive roller 39, the pinch roller 40 also rotates together with the drive roller 39. Therefore, when a sheet is fed between the drive roller 39 and the pinch roller 40 while the transport motor 49 is driven, the sheet is nipped between the drive roller 39 and the pinch roller 40. Therefore, by rotating the drive roller 39 and the pinch roller 40 in this nip state, it is possible to convey the paper in the conveying direction.

On the other hand, when the motor gear 54 is rotated by the driving of the side shift motor 55, this rotational force is transmitted to the rack member 50 via the pinion gear 53.
As a result, the pinion gear 53 along with the motor gear 54
With rotation, the rotational movement of the pinion gear 53 is converted into the linear movement of the rack member 50. for that reason,
The rack member 50 moves in a direction orthogonal to the transport direction, and the roller shaft 41 and the drive roller 39 follow this movement.
Also moves in the same direction. Therefore, as described above, the sheet is nipped between the drive roller 39 and the pinch roller 40, and the side shift motor 55 is driven in this state to move (side shift) the sheet in the direction orthogonal to the transport direction. You can

Here, when the sheet 35 fed through the sheet aligning section 26 is side-shifted by the movement of the registration roller 27, first, the registration roller 27 is moved.
The rollers 39 and 40 constituting the above are arranged at the home position which is the movement start position. In this way, each roller 39,
In the state where 40 is arranged at the home position, the rack member 50 is abutted against the retaining ring 62 by the biasing force of the coil spring 59. Therefore, the rack member 50 is supported on the roller shaft 41 without rattling.

Further, the abutting force of the coil spring 59 against the retaining ring 62 becomes an urging force for urging the roller shaft 41 in one direction (rightward in FIG. 4). On the other hand, the spring force of the coil spring 63 serves as a biasing force that biases the roller shaft 41 in the other direction (leftward in FIG. 4). In this case, the coil spring 6
Since the urging force of 3 is set to be larger than the urging force of the coil spring 59, the roller shaft 41 receives a force in the direction urged by the coil spring 63 (leftward in FIG. 4). Therefore, at the meshing portion of the gear portion 50A of the rack member 50 and the small-diameter gear portion 53B of the pinion gear 53, the tooth surfaces are in contact with each other by the biasing force of the coil spring 63.

Next, when the side shift operation is executed, the driving of the side shift motor 55 is started while the rollers 39 and 40 are arranged at the home positions as described above. During the side shift operation by the motor drive, FIG.
As shown in, the motor gear 54 rotates in the counterclockwise direction in the figure, and accordingly the pinion gear 53 rotates in the clockwise direction in the figure. Further, when the pinion gear 53 rotates, the rack member 50 moves accordingly in the right direction in the drawing.

At this time, the rack member 50 is in contact with the retaining ring 62 by the urging force of the coil spring 59. Therefore, when the rack member 50 moves due to the rotation of the pinion gear 53, the roller shaft is moved accordingly. 41 also moves to the right in the figure. The direction of movement of the roller shaft 41 during this side shift operation (during sheet position adjustment operation) is the same as the direction in which the biasing force of the coil spring 59 applied to the roller shaft 41 via the rack member 50 acts. When the roller shaft 41 moves, the coil spring 63 is compressed by the amount of the movement, and the reaction force F1 due to this compression is applied to the roller shaft 41. Therefore, during the side shift operation, the gear portion 50A of the rack member 50 and the small diameter gear portion 53B of the pinion gear 53 are always held in a state where the same tooth surfaces are in contact with each other.

When a predetermined time elapses after the side shift operation is started, the side shift motor 55 stops driving, and accordingly, the rotations of the motor gear 54 and the pinion gear 53 also stop. In this case, the motor drive stop timing is set to the sheet side edge detection sensor 38 shown in FIG.
It is controlled based on the detection signal from.

At this time, the roller shaft 41 and the rack member 50
Since an inertial force due to the driving stop of the side motor 55 acts on the roller shaft 41 and the rack member 50, the inertial force causes the roller shaft 41 and the rack member 50 to move in the rightward direction in FIG. Try to move to. However, since the reaction force F1 due to the compression of the coil spring 63 is applied to the roller shaft 41 and this reaction force F1 is also applied to the rack member 50 via the retaining ring 62, the roller shaft 41 is temporarily moved by the inertia force. Even if it moves to the right of, it is pulled back by the reaction force F1.

After that, when the registration roller 27 is returned to the home position, the side shift motor 55 is restarted by reversing the rotation direction at the start of the side shift operation. As a result, as shown in FIG.
Rotates in the clockwise direction in the figure, and accordingly the pinion gear 53 rotates in the counterclockwise direction in the figure. Further, when the pinion gear 53 rotates, the rack member 50 moves leftward in the figure accordingly.

At this time, since the coil spring 59 is compressed by the movement of the rack member 50, the reaction force F2 due to this compression acts on the rack member 50. Therefore, the rack member 50 moves while receiving the reaction force F2 as a resistance force. When the rack member 50 moves to the left in the figure, the roller shaft 41 also moves in the same direction following this. In this case, the roller shaft 41 is moved by the biasing force of the coil spring 63. As a result, during the returning operation to the home position, the rack member 50
Gear part 50A and small diameter gear part 53B of pinion gear 53
And are always held in a state where the same tooth surfaces are in contact with each other.

When a predetermined time elapses after the return operation to the home position is started, the side shift motor 55 is stopped and the motor gear 54 is accordingly stopped.
The rotation of the pinion gear 53 also stops. The motor drive stop timing in this case is controlled based on a detection signal from a home position sensor (not shown).

At this time, the roller shaft 41 and the rack member 50
Since an inertial force due to the driving stop of the side motor 55 acts on the roller shaft 41 and the rack member 50, the inertial force causes the roller shaft 41 and the rack member 50 to move in the leftward direction in FIG. 6 by the amount of the backlash of the meshing portion of the rack member 50 and the pinion gear 53. Try to move to. However, since the reaction force F2 due to the compression of the coil spring 59 is applied to the rack member 50, even if the rack member 50 moves to the left in the figure by the inertial force,
It is pushed back by the reaction force F2.

On the other hand, an inertial force acts on the roller shaft 41 in the leftward direction in the figure, and the spring force of the coil spring 63 is applied in the same direction as the inertial force. Therefore,
When the registration roller 27 is moved to the home position, the spring force of the coil spring 63 acts on the rack member 50 via the retaining ring 62, which causes the gear member 50A of the rack member 50 to move in the same manner as at the start of the side shift operation. The tooth surfaces of the pinion gear 53 and the small diameter gear portion 53B are in contact with each other.

As a result, from the start to the end of the side shift operation, there is rattling of the roller shaft 41 and the rack member 50, inertia force acting when the movement is stopped (when the side shift motor 55 is stopped), and further the rack. It is possible to reliably prevent the positional deviation of the registration roller 27 due to the backlash between the member 50 and the pinion gear 43. Therefore, it is possible to suppress variations in the stop position of the registration roller 27.

Further, the coil springs 59 and 63 are connected to the roller shaft 4
Since the structure is provided on the roller 1, it is not necessary to secure a space for mounting the spring in the peripheral portion of the roller shaft 41. Therefore, it is possible to save the space for mounting the parts.

[0060]

As described above, according to the sheet conveying device of the present invention, the roller shaft is urged by the first urging means through the first gear member in the direction orthogonal to the conveying direction, and By urging the roller shaft in the direction opposite to the urging direction of the first urging means by the urging force of the second urging means, it is possible to suppress the variation of the stop position of the conveying roller and improve the alignment accuracy of the sheets. You can As a result, the sheet nipped by the conveying roller can be accurately aligned with a desired position in the direction orthogonal to the sheet conveying direction. Further, in the image forming apparatus provided with such a sheet conveying device, the sheet and the image can be accurately aligned (aligned) in the direction orthogonal to the conveying direction.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a configuration example of an image forming apparatus to which the present invention is applied.

FIG. 2 is a schematic diagram showing a configuration of a sheet aligning unit according to the embodiment of the present invention.

FIG. 3 is a schematic perspective view showing a mechanical configuration including a roller moving mechanism.

FIG. 4 is an enlarged view showing a main part of a roller moving mechanism.

FIG. 5 is a diagram (No. 1) for explaining the operation of the roller moving mechanism.

FIG. 6 is a diagram (No. 2) for explaining the operation of the roller moving mechanism.

[Explanation of symbols]

27 ... Registration roller, 39 ... Drive roller, 40 ...
Pinch rollers, 41, 42 ... Roller shafts, 50 ... Rack members, 53 ... Pinion gears, 54 ... Motor gears, 55 ... Side shift motors, 59 ... Coil springs (first biasing means), 62 ... Retaining rings, 63 ... Coil springs (Second urging means)

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Michio Tada             Fuji Zero, 2274 Hongo, Ebina City, Kanagawa Prefecture             Co., Ltd. Ebina Office (72) Inventor Yutaka Kazama             Fuji Zero, 2274 Hongo, Ebina City, Kanagawa Prefecture             Co., Ltd. Ebina Office (72) Inventor Takuzen Kimura             Fuji Zero, 2274 Hongo, Ebina City, Kanagawa Prefecture             Co., Ltd. Ebina Office F-term (reference) 2H072 AB13 CA01 CB09 HB07                 3F049 AA02 CA23 CA33 DA12 DB04                       LA02 LA07 LB03                 3F102 AA02 AA11 AB01 BA01 BA09                       BB04 BB07 EA03 EA06 FA03

Claims (5)

[Claims] 1. A conveyance roller for nipping and conveying a sheet, a first gear member movably provided on a roller shaft of the conveyance roller in an axial direction of the roller shaft, and the first gear member. A moving unit that has a power transmission mechanism that includes a second gear member that meshes, and that moves the transport roller in a direction orthogonal to the sheet transport direction integrally with the roller shaft via the power transmission mechanism; A first urging means for urging the roller shaft in a direction orthogonal to the conveying direction via one gear member; and a roller shaft in a direction opposite to the urging direction of the first urging means. A sheet conveying apparatus comprising: a second urging unit that urges the sheet. 2. The sheet conveying apparatus according to claim 1, wherein the first and second urging means are provided on the roller shaft. 3. The urging force of the second urging means is set to the first urging force.
The sheet conveying apparatus according to claim 1, wherein the urging force is set to be larger than the urging force of the urging means. 4. The sheet conveying method according to claim 1, wherein the urging force of the second urging means is set to be larger than the movement resistance force of the roller shaft in the direction orthogonal to the conveying direction. apparatus. 5. An image forming apparatus comprising the sheet transporting device according to claim 1, 2, 3 or 4.